Reconfigurable quasi-optical unit cells

ABSTRACT

A quasi-optical system is provided. More specifically, a quasi-optical system is provided comprising various embodiments of quasi-optical grids (such as arrays or layers and the like) with reconfigurable quasi-optical unit cells. The quasi-optical system, grids and unit cells are configured to control an incident beam in a variety of ways.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of Provisional application Ser. Nos.60/138,865, filed Jan. 11, 1999, and 60/173,659, filed Dec. 30, 1999.

This patent application is related to copending PCT patent applicationsSer. Nos. PCT/US00/16021 and PCT/US00/16023 having respective attorneydocket nos. FP-68000/JAS/SMK and FP-68677/JAS/SMK, with respectivetitled MEMS TRANSMISSION AND CIRCUIT COMPONENTS and MEMS OPTICALCOMPONENTS, and filed on Jun. 9, 2000. These copending applications arehereby incorporated by reference.

TECHNICAL FIELD OF THE INVENTION

The present invention relates generally to quasi-optical systems. Inparticular, the present invention pertains to a quasi-optical systemcomprising quasi-optical grids (i.e., arrays or layers) withreconfigurable quasi-optical unit cells.

BACKGROUND OF THE INVENTION

To accommodate bandwidth and resolution demands, future communicationnetworks are likely to migrate toward operating frequencies atcorresponding millimeter and sub-millimeter wavelengths. In the past,the lack of high-frequency semiconductor devices has prevented thedevelopment of such high-frequency systems. However, recent advances insemiconductor device technology have allowed integrated circuits tooperate at as high as 300 GHz for transistors and 1.0 THz for diodes. Inany working system, transmitters must be capable of efficientlyproviding sufficient power and the receivers must be able to handlesignals of widely varying strength without sacrificing sensitivity. Itseems exceedingly difficult to meet these demands using conventionalmicrowave power-combining techniques.

One promising approach for realizing millimeter and sub-millimeterwavelength high power systems is quasi-optical power combining This isan elegant technique to integrate many active devices into a free-spacepower combining component. Hundreds, possibly thousands, of solid-statehigh speed devices could be incorporated through wafer scale integrationto generate high power. Quasi-optical wireless systems are particularlyattractive because they allow the front-end components to beinexpensively mass produced and they don't require single modewaveguides, thereby allowing higher operating frequencies.

One of the key components in a complete quasi-optical system is the beamcontroller. The beam controller is used to control a beam by steering,focusing, splitting, switching, and/or shaping the beam. For example,the beam controller is used in systems employing radar for aircraftguidance, missile seeking, and automobile collision avoidance.Similarly, the beam controller is necessary in a millimeter wavelengthimaging camera that sees through fog. In these systems, high speedcontrol of a beam is necessary so that more targets can be tracked orimaged simultaneously.

In the past, beam switching has been demonstrated with beam switchescomprising grids with PIN diodes. However, the configuration of thegrids prevents them from being used to steer, focus, and/or shape beams.

Furthermore, beam controllers comprising grids with Schottky diodes havealso been developed in the past for reflective steering of beams.However, the series resistance of the Schottky diodes increases when theoperating frequencies increase. This causes significant reflectionlosses and prevents these beam controllers from being used at shorterwavelengths for a low loss system.

Therefore, there is a need for a quasi-optical beam controller that canefficiently operate at millimeter and sub-millimeter wavelengths withoutsignificant losses. Such a beam controller would ideally providetransmission type steering, focusing, and/or shaping of beams.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows one configuration for a quasi-optical system, namely aquasi-optical beam controller, in accordance with the present invention.

FIG. 2 shows a quasi-optical grid that can be used in the beamcontroller of FIG. 1.

FIG. 3 shows the equivalent circuit of each quasi-optical unit cell ofthe grid of FIG. 2.

FIG. 4 shows one configuration for each unit cell of FIG. 2 in order toimplement the equivalent circuit of FIG. 3.

FIG. 5 shows the configuration of a reconfigurable conductive strip ofthe unit cell of FIG. 4.

FIGS. 6 to 8 show the configuration of an actuator assembly of the unitcell of FIG. 4.

FIGS. 9 to 11 show the configuration of a MEMS see-saw switch of theunit cell of FIG. 4.

FIGS. 12 and 15 show other quasi-optical grids that can be used in thebeam controller of FIG. 1.

FIG. 13 shows the equivalent circuit of each quasi-optical unit cell ofthe grids of FIGS. 12 and 15.

FIG. 14 shows one configuration for each unit cell of FIGS. 12 and 15 inorder to implement the equivalent circuit of FIG. 13.

FIG. 16 shows yet another quasi-optical grid that can be used in thebeam controller of FIG. 1.

FIG. 17 shows one configuration for each unit cell of FIG. 16 in orderto implement the equivalent circuit of FIG. 13.

SUMMARY OF THE INVENTION

In summary, the present invention comprises various embodiments for aquasi-optical system, a quasi-optical grid for use in the quasi-opticalsystem, and a quasi-optical unit cell for use in the quasi-optical grid.The quasi-optical system, grid, and unit cell are used to control anincident beam.

In one embodiment, the quasi-optical unit cell comprises an inductiveconductive strip configured to provide an inductive reactance andcapacitive conductive strips to provide a capacitive reactance. In thisembodiment, at least one of the inductive strip and the capacitivestrips are controllably reconfigurable by a control circuit of thequasi-optical system to provide the unit cell with a variable overallreactance for producing a variable phase shift in the incident beam.

In another embodiment, the quasi-optical unit cell comprises aninductive conductive strip configured to provide an inductive reactance,capacitive conductive strips configured to provide a capacitivereactance, and a switch configured to provide a switching function. Inthis embodiment, the unit cell has an overall reactance in which theinductive reactance and the switching function are in series with eachother and in parallel with the capacitive reactance. Thus, the overallreactance is primarily inductive or primarily capacitive when the switchis controlled by a control circuit of the quasi-optical system so thatthe switching function is on or off. The inductive and capacitive stripsare configured so that the overall reactance causes a phase shift in butnot an amplitude distortion in the incident beam.

In still another embodiment, the quasi-optical unit cell comprises asubstrate having opposite first and second sides, a first dielectriclayer on the first side of the substrate, a second dielectric layer onthe second side of the substrate, an inductive conductive strip on thefirst dielectric layer that is configured to provide an inductivereactance, capacitive conductive strips on the second dielectric layerconfigured to provide a capacitive reactance, and a switch on the firstdielectric layer that is configured to provide a switching function. Theunit cell has an overall reactance in which the inductive reactance andthe switching function are in series with each other and in parallelwith the capacitive reactance. The overall reactance is primarilyinductive or primarily capacitive when the switch is controlled so thatthe switching function is on or off.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIG. 1, there is shown a configuration of one type ofquasi-optical system, namely a quasi-optical beam controller 100,according to the present invention. The beam controller 100 comprisesquasi-optical grids (i.e., arrays or layers) 101, 146, 152 and/or 154and a control circuit 103. The grids 101, 146, 152 and/or 154 arestacked in parallel and spaced at quarter wavelengths. A beam 104radiating in free space enters the beam controller 100 and passesthrough the grids 101. The grids 101, 146, 152 and/or 154 control thebeam 104 under the control of the control circuit 103. This control ofthe beam 104 may include any combination of steering, focusing,splitting, switching, shaping, and/or some other type of altering of thebeam 104. The beam 104 then exits the beam controller 100 and radiatesback into free space.

The grids 101, 146, 152 and/or 154 are used to control the beam 104 inthe corresponding propagation plane of its electric field (hereafter“E_(b)-plane”) and/or the corresponding propagation plane of itsmagnetic field H_(b) (hereafter “H_(b)-plane”). In doing so, each grid101, 146, 152 and/or 154 is controlled by the control circuit 103 tocauses a corresponding phase shift in the beam 104 in the E_(b)-planeand/or H_(b)-plane. In this way, the total phase shift in theE_(b)-plane and/or H_(B)-plane that occurs across the grids 101, 146,152 and/or 154 comprises progressive phase shifts and provides theoverall control of the beam 104 in the E_(b)-plane and/or H_(b)-plane.

As those skilled in the art will appreciate, the number and the type ofgrids 101, 146, 152 and/or 154 used in the beam controller 100 willdepend on the amount and type of control of the beam 104 that isdesired. Thus, the beam controller 100 could include any combination ofone or more grids 101, 146, 152 and/or 154 for controlling the beam 104in its E_(b)-plane and/or H_(b)-plane simultaneously and/or separately.

Grids 101

Referring to FIG. 2, each of the grids 101 comprises reconfigurable unitcells 105. The unit cells 105 of each grid 101 are integrally formedtogether in a configuration to produce beam control in the E_(b)-planeand/or H_(b)-plane of the beam 104 of FIG. 1.

Each unit cell 105 is controllably reconfigurable by the control circuit103 of FIG. 1 to have a variable overall reactance for producing acorresponding variable unit wide phase shift in the beam 104 of FIG. 1in the E_(b)-plane or H_(b)-plane. By reconfiguring each unit cell 105to have a selected overall reactance, a corresponding selected unit widephase shift in the E_(b)-plane or H_(b)-plane is achieved with the unitcell 105. Each grid 101 can therefore provide a selected discrete phaseshaft in the E_(b)-plane and/or H_(b)-plane by controllablyreconfiguring the unit cells 105 of the grid 101 to have variousselected overall reactances. In this way, if multiple grids 101 are usedin the beam controller of FIG. 1, the total phase shift in theE_(b)-plane and/or H_(b)-plane that occurs across the grids 101comprises progressive discrete phase shifts. FIG. 3 shows the equivalentcircuit of each unit cell 105. To provide the overall variablereactance, each unit cell 105 has a shunt variable inductive reactanceL_(v), a shunt variable capacitive reactance C_(v), and a switchingfunction S. The switching function S is electrically connected in serieswith the inductive reactance L_(v). The capacitive reactance C_(v) iselectrically connected in parallel with the in series electricalconnection of the inductive reactance L_(v) and the switching functionS. The overall reactance of the unit cell 105 can be varied byappropriately turning on or off the switching function S and/or byvarying the inductive reactance L_(v) and/or the capacitive reactanceC_(v).

FIG. 4 shows one possible configuration for each unit cell 105 toprovide the equivalent circuit of FIG. 3. Each unit cell 105 comprises aMEMS (micro-machined electromechanical systems) reconfigurable inductiveconductive strip 106 and two parallel MEMS reconfigurable capacitiveconductive strips 107, and a MEMS see-saw switch 108. As shown in FIGS.5 to 11, each unit cell 105 also comprises a corresponding portion ofthe semiconductor substrate 109 and dielectric layer 110 of thecorresponding grid 101 of FIG. 2. The reconfigurable inductive andcapacitive strips 106 and 107 and the switch 108 are formed on thedielectric layer 110.

The reconfigurable inductive conductive strip 106 provide the variableinductive reactance L_(v) in the equivalent circuit of FIG. 3. Thisinductive reactance L_(v) produces a magnetic field H_(L) in acorresponding control plane (hereafter “H_(L)-plane”). Thereconfigurable inductive strip 106 has a fixed length l_(n) in the Xdirection and a variable width w_(vl), in the Y direction. As will bediscussed next, the reconfigurable inductive strip 106 can bereconfigured to vary the width w_(vl) so as to correspondingly vary theinductive reactance L_(v),. However, to provide the selected unit widephase shift in the beam 104 of FIG. 1, the length In and the widthw_(vl) must be such that only phase change occurs in the beam 104 butnot amplitude change. Thus, the length l_(n) is preferably about 20 mmand the width w_(vl) can be preferably varied around about 2.3 mm for aunit cell of 20 mm per side to provide a binary unit wide phase shift of22.5° at 5 GHz in the beam 104 of FIG. 1 in the E_(b)-plane or theH_(b)-plane with phase change and not amplitude change of the beam 104.

Referring back to FIG. 4, the reconfigurable inductive strip 106comprises two lower conductive strips 111, two upper conductive strips112, and two actuator assemblies 114. The lower and upper conductivestrips 111 and 112 all extend in the X direction. Each lower conductivestrip 111 is fixedly coupled to the dielectric layer 110. Each upperconductive strip 112 is electrically connected to and slidably moveableon a corresponding lower strip 111. Furthermore, each upper conductivestrip 112 is fixedly coupled to a corresponding actuator assembly 114.Each actuator assembly 114 is controlled by the control circuit 103 ofFIG. 1 to cause the corresponding upper conductive strip 112 to slidablymove on the corresponding lower conductive strip 111.

As shown in FIG. 5, each lower conductive strip 111 comprises asemiconductor strip 115 formed on the dielectric layer 110. Each upperconductive strip 112 comprises a semiconductor strip 116 and a metalplating 117 formed on the semiconductor strip 116. The semiconductorstrip 116 is electrically connected to and slidably moveable on thesemiconductor strip 115. To do so, the semiconductor strip 116 comprisescontact rails (not shown) like the contact rails 132 of the guide arm129 of FIG. 6. This minimizes friction and stiction. These rails may becontinuous or may comprise a row of protrusions or bumps. The metalplating 117 is used to reduce the resistivity of the upper conductivestrip 112 caused by the semiconductor strip 116 so as to avoid losses atmillimeter and/or sub-millimeter wavelength frequencies of the beam 104of FIG. 1.

Referring again to FIG. 6, each actuator assembly 114 comprises actuatorsub-assemblies 118 and an insulating attachment bridge 119. One of theactuator sub-assemblies 118 is configured for forward movement and theother is configured for backward movement. Each actuator sub-assembly118 comprises a conductive support frame 120 that is fixedly coupled tothe support frame 120 of the other actuator sub-assembly 118 with theinsulating attachment bridge 119. The insulating attachment bridge 119fixedly couples, but electrically isolates, the support frames 120 ofthe actuator sub-assemblies 118.

Each actuator sub-assembly 118 also comprises an array of SDAs(scratch-drive actuators) 121 and conductive flexible attachment arms122. Each SDA 121 is fixedly coupled and electrically connected to thesupport frame 120 of the actuator sub-assembly 118 by correspondingattachment arms 122.

As shown in FIGS. 7 and 8, each SDA 121 comprises a corresponding plate123 and a corresponding bushing 124. The plate 123 is fixedly coupledand electrically connected to corresponding attachment arms 122 and maybe integrally formed with these attachment arms 122. The attachment arms122 are themselves fixedly coupled and electrically connected to thesupport frame 120 of the corresponding actuator sub-assembly 118 by vias125 of the actuator sub-assembly 118.

Referring back to FIG. 6, the SDAs 121 of each actuator sub-assembly 118are aligned for forward or backward movement depending on whether theactuator sub-assembly 118 is to be used for forward or backwardmovement. The SDAs 121 are of the type described in T. Akiyamna and K.Shono, “Controlled Stepwise Motion in Polysilicon Microstructures”, J.of MEMS, Vol. 2, No. 3, pp. 106, September 1993, and T. Akiyama and H.Fujita, “A Quantative Analysis of Scratch Drive Actuator Using BucklingMotion”, IEEE Micro Electro Mechanical Systems, pp. 310-315, 1995. Thesearticles are hereby incorporated by reference.

Referring again to FIGS. 7 and 8, each actuator sub-assembly 118 alsocomprises conductive contact rails 126 and conductive bias lines 127.The contact rails 126 are fixedly coupled to and patterned on the lowersurface of the support frame 120 of the actuator sub-assembly 118 and,in fact, may be integrally formed with the support frame 120. Thecontact rails 126 are also electrically connected to the support frame120. The bias lines 127 are fixedly coupled to and patterned on thedielectric layer 110. The contact rails 126 moveably slide on andelectrically contact the bias lines 127.

Turning now to FIGS. 6 to 8, the conductive plates 123 of the SDAs 121of each actuator sub-assembly 118 are electrically connected to the biaslines 127 of the actuator sub-assembly 118 via the contact rails 126,support frame 120, and attachment arms 122 of the actuator sub-assembly118. Thus, when a periodic square wave bias signal is applied to thebias lines 127 by the control circuit 103 of FIG. 1, this signal isprovided to the plates 123. Since the semiconductor substrate 109 isgrounded, this causes the plates 123 to be pulled down toward thedielectric layer 110 each time the signal reaches a high voltage. Theplates 123 are pulled down because of the flexure in the flexibleconductive attachment arms 122. Each time this occurs, the bushings 124of the SDAs 121 reach out and contact the dielectric layer 110. Then,each time the signal goes to a low voltage, the plates 123 return totheir original positions and the bushings 124 pull the entire actuatorassembly 114 forward or backward a step depending on whether theactuator sub-assembly 118 is configured for forward or backwardmovement. In this way, the entire actuator assembly 114 moves forward orbackward in a stepwise fashion.

Referring back to FIG. 6, each actuator assembly 114 also compriseslower guide arms 128, upper guide arms 129, and insulating attachmentbridges 130, and guiding overhangs 131. As shown in FIG. 7, each lowerguide arm is fixedly coupled to the dielectric layer 110 and, as shownin FIG. 4, may be integrally formed with a corresponding lowerconductive strip 111 of the reconfigurable inductive strip 106. Eachupper guide arm 129 slidably moves on a corresponding lower guide arm128. To do so, each upper guide arm 129 comprises a contact rail 132 tominimize friction and stiction. Each rail 145 may be continuous or maycomprise a row of protrusions or bumps. Each upper guide arm 129 isfixedly attached to the support frame 120 of a corresponding actuatorsub-assembly 118 by a corresponding insulating attachment bridge 130.

As shown in FIG. 4, each upper guide arm 129 is also fixedly coupled toa corresponding upper conductive strip 112 of the reconfigurableinductive strip 106 and may be integrally formed with the semiconductorstrip 116 of this upper conductive strip 112. As a result, each actuatorassembly 114 is fixedly coupled to the corresponding upper conductivestrip 112 by the corresponding upper guide arms 129 and the insulatingattachment bridges 130.

Referring back to FIG. 6, each actuator assembly 114 further comprisesguiding overhangs 131. As shown in FIG. 7, each guiding overhang 131 isfixedly coupled to a corresponding lower guide arm 128 by an anchor 133of the actuator assembly 114. This enables the guiding overhang 131 toextend up from the corresponding guide arm 128 along the outer surfaceand over the upper surface of the corresponding upper guide arm 129.Referring again to FIG. 6, the guiding overhangs 131 collectively guidethe entire actuator assembly 114 as it moves forward or backward.

Referring now to FIG. 4, each upper conductive strip 112 can thereforebe slidably moved on the corresponding lower conductive strip 111 byappropriately controlling the corresponding actuator assembly 114.Specifically, when the control circuit 103 of FIG. 1 applies a forwardmovement bias signal between the bias lines 127 of the actuatorsub-assembly 118 used for forward movement and the semiconductorsubstrate 109 of FIG. 6, the entire actuator assembly 114 moveslaterally forward to push the upper conductive strip 112 forward.Similarly, when the control circuit 103 applies a backward movement biasvoltage between the bias lines 127 of the actuator sub-assembly 118 usedfor backward movement and the semiconductor substrate 109, the entireactuator assembly 114 moves backward so as to pull the upper conductivestrip 112 backward.

The control circuit 103 of FIG. 1 can therefore controllably cause bothupper conductive strips 112 to move simultaneously laterally forward orbackward. This correspondingly increases or decreases the width w_(vl)of the reconfigurable inductive strip 106 so as to correspondinglyincrease or decrease the inductive reactance L_(v) of FIG. 3 provided bythe reconfigurable inductive strip 106. In this way, the inductivereactance L_(v) of the reconfigurable inductive strip 106 can becontrollably varied.

In alternative embodiment, each actuator assembly 114 could comprise anarray of side-drive actuators, such as those described in L. Fan, Y. C.Tai, and R Muller, “IC Processed Electrostatic Micromotors”, Sensors andActuators, Vol. 20, pp. 41-47, November 1989. Or, each actuator assembly114 could comprise an array of comb-drive actuators, such as thosedescribed in W. tang, T. Nguyen, and R. Howe, “Laterally DrivenPolysilicon Resonant Microstructures”, Sensors and Actuators, Vol. 20,pp. 25, November 1989. Both of these articles are hereby incorporated byreference. Additionally, thermal actuators, piezoelectric actuators, andelectromagnetic actuators could also be used.

Referring back to FIG. 4, the reconfigurable conductive strips 107 formthe variable capacitive reactance C_(v) in the equivalent circuit ofFIG. 3. This capacitive reactance C_(v) produces an electric field E_(C)in a corresponding control plane (hereafter “E_(C)-plane”). Eachreconfigurable capacitive strip 107 has a fixed length l_(f2) in the Ydirection and a variable width w_(v2) in the X direction. The capacitivereactance C_(v) is related to a variable gap g_(v) between thereconfigurable conductive strips 107. As will be discussed next, eachreconfigurable capacitive strip 107 can be reconfigured to vary thewidth w_(v2) so as to correspondingly vary the gap g_(v) and therebycorrespondingly vary the capacitive reactance C_(v). Here as well, toprovide the selected phase shift in the beam 104 of FIG. 1, the lengthl_(n) and the width w_(vl) must be such that only phase change occurs inthe beam 104 but not amplitude change. The length l_(f2) is preferablyabout 20 mm. The width w_(v2) can be preferably varied between about 1mm for a unit cell size of 20 mm per side to provide a binary unit widephase shift of 22.5° at 5 GHz in the beam 104 of FIG. 1 in theE_(b)-plane or the H_(b)-plane with phase change and not amplitudechange of the beam 104.

Referring back to FIG. 4, each reconfigurable capacitive conductivestrip 107 is configured similar to the reconfigurable inductive strip106 and comprises two lower conductive strips 134, two upper conductivestrips 135, and two actuator assemblies 114. The lower and upperconductive strips 134 and 135 all extend in the Y direction.

Each lower conductive strip 134 is fixedly coupled to the dielectriclayer 110. Furthermore, each lower conductive strip 134 is configuredlike a lower conductive strip 111 of the reconfigurable inductive strip106 of FIG. 5 in that it comprises a semiconductor strip formed on thedielectric layer 110.

Each upper conductive strip 135 is electrically connected to andslidably moveable on a corresponding lower conductive strip 134. Eachupper conductive strip 135 is configured like an upper conductive strip112 of the reconfigurable inductive strip 106 of FIG. 5. Specifically,each upper conductive strip 135 comprises a semiconductor strip and ametal plating formed on the semiconductor strip. The semiconductor stripof the upper conductive strip 135 is electrically connected to andslidably moveable on the semiconductor strip of the corresponding lowerconductive strip 134. As with the reconfigurable inductive strip 106,the metal plating is used to reduce the resistivity of the upperconductive strip 134 caused by the semiconductor strip so as to avoidlosses at millimeter and/or sub-millimeter wavelength frequencies of thebeam 104 of FIG. 1.

Each upper conductive strip 135 is fixedly coupled to a correspondingactuator assembly 114. This is done in the same manner that each upperconductive strip 112 of the reconfigurable inductive strip 106 isfixedly coupled to a corresponding actuator assembly 114. Each actuatorassembly 114 is controlled by the control circuit 103 of FIG. 1 to causethe corresponding upper conductive strip 135 to slidably move on thecorresponding lower conductive strip 134. This is done in the same waythat each upper conductive strip 112 of the reconfigurable inductivestrip 106 slidably moves on the corresponding lower conductive strip111.

The control circuit 103 can therefore controllably cause the upperconductive strips 135 of one or both reconfigurable conductive strips107 to move simultaneously laterally forward or backward. Thiscorrespondingly increases or decreases the width w_(v2) of eachreconfigurable capacitive strips 106 whose upper conductive strips 135are moved. As a result, the gap g_(v) between the reconfigurableconductive strips 107 is correspondingly increased or decreased so thatthe capacitive reactance C_(v) of FIG. 3 provided by the reconfigurableconductive strips 107 is also correspondingly increased or decreased. Inthis way, the capacitive reactance C_(v) can be controllably varied.

As shown in FIG. 4, the opposing internal ends of the lower conductivestrips 134 and the opposing internal ends of the upper conductive strips135 of each reconfigurable capacitive conductive strip 107 are spacedapart to provide a small gap 136 in each reconfigurable capacitiveconductive strip 107. The external ends of corresponding upper and lowerconductive strips 111 and 112 of the reconfigurable inductive strip 106extend into the gap 136 of each reconfigurable capacitive conductivestrip 107. This increases the length of the reconfigurable inductivestrip 106 and therefore the inductive reactance L_(v) of FIG. 3 providedby the reconfigurable inductive strip 106.

Each unit cell 105 also comprises small interconnects 137. The lowerconductive strips 134 of each reconfigurable capacitive strips 106 and acorresponding lower conductive strip 111 of the reconfigurable inductivestrip 106 are fixedly coupled together and electrically connectedtogether by a corresponding small interconnect 137. Specifically, eachsmall interconnect 137 extends across a corresponding gap 136 at theouter edge of the unit cell 105 and fixedly couples and electricallyconnects the opposing internal ends of the corresponding lowerconductive strips 134 and the external end of the corresponding lowerconductive strip I1.

In an alternative embodiment for each unit cell 105, there could be nophysical coupling between the lower conductive strips 134 of eachreconfigurable capacitive conductive strip 107 and the correspondinglower conductive strip 111 of the reconfigurable inductive conductivestrip 106. However, for the propagating waves of the beam 104 of FIG. 1,an electrical connection still exists so that the equivalent circuitwould still be that shown in FIG. 3.

Still referring to FIG. 4, the see-saw switch 108 provides the switchingfunction S in the equivalent circuit of FIG. 3 to electrically connectand disconnect the inductive reactance L_(v). The see-saw switch 108 iselectrically connected in series with the lower conductive strips 111 ofthe reconfigurable inductive strip 106. The reactance of the unit cell105 can be made primarily inductive by causing the see-saw switch 108 toelectrically connect the lower conductive strips 111 of thereconfigurable inductive strip 106 so as to close the switching functionS. The reconfigurable inductive strip 106 is therefore electricallyconnected between the reconfigurable conductive strips 107 and theinductive reactance L_(v) of FIG. 3 provided by the reconfigurableinductive strip 106 dominates the overall reactance of the unit cell105. Conversely, the overall reactance of the unit cell 105 can be madeprimarily capacitive by causing the see-saw switch 108 to electricallydisconnect the lower conductive strips 111 so as to open the switchingfunction S. As a result, the reconfigurable inductive strip 106 iselectrically disconnected between the reconfigurable conductive strips107 and the capacitive reactance C_(v) of FIG. 3 provided by thereconfigurable conductive strips 107 dominates the overall reactance ofthe unit cell 105.

As shown in FIGS. 9 to 11, the see-saw switch 108 comprises anelectrical contact 144, an insulating attachment arm 145, a pivot arm(or bar) 138, electrodes 139 and 140, and a spring hinge 141. The pivotarm 138 extends between the support bases 143 along a longitudinal axisA_(L) that is transverse (i.e., perpendicular) to a rotation axis A_(R)at the center of the pivot arm 138. One end of the pivot arm 138 isfixedly coupled to the insulating attachment arm 145. The insulatingattachment arm 145 fixedly couples and electrically isolates theelectrical contact 144 from the pivot arm 138. The electrodes 139 and140 are fixedly coupled to the dielectric layer 110 and are locatedunderneath opposite ends of the pivot arm 138. Thus, there is acorresponding end of the pivot arm 138 for each electrode 139 and 140.The spring hinge 141 pivotably couples the center of the pivot arm 138to the dielectric layer 110 so that both ends of the pivot arm 138 canpivot about the rotation axis A_(R).

The electrical contact 144 comprises a semiconductor strip 370 and ametal strip 372. The metal strip 372 is formed on the underside of thesemiconductor strip 370. The semiconductor strip 370 is also fixedlycoupled to the insulating attachment arm 145.

The spring hinge 141 comprises spring arms 142 and two support bases143. The spring arms 142 extend out from the center of the pivot arm 138in opposite directions along the rotation axis A_(R). Each spring arm142 has one end fixedly coupled to the center of the pivot arm 138.These ends of the spring arms 142 may be integrally formed and joinedtogether. The other end of each spring arm 142 is fixedly coupled to acorresponding support base 143 with an anchor 133. The spring arms 142suspend the pivot arm 138 over the dielectric layer 110 and theelectrodes 139 and 140. Moreover, the spring arms 142 are patterned(i.e., configured) to provide the spring hinge 141 with the same springconstant for both clockwise and counterclockwise pivoting by the ends ofthe pivot arm 138. As a result, the ends of the pivot arm 138 can pivotabout the rotation axis A_(R). Furthermore, the support bases 143, thespring arms 142, and the pivot arm 138 are all conductive.

In order to close the see-saw switch 108, a voltage is applied across atleast one of the support bases 143 and the electrode 139. Since thepivot blocks 142, the hinge pin 140, and the pivot arm 138 are allconductive, this voltage appears between the electrode 139 and thecorresponding end of the pivot arm 140. The resulting electrostaticforce overcomes the spring force of the spring hinge 141 due to thespring constant and causes the corresponding end to pivot via the pivothinge 141 about the rotation axis A_(R). The corresponding end istherefore pulled down toward the electrode 139 until the electricalcontact 144 is laid down on and contacts the lower conductive strips 111of the reconfigurable inductive strip 106. As a result, the lowerconductive strips 111 are electrically connected. Conversely, a voltageis applied across at least one of the support bases 143 and theelectrode 140 to open the see-saw switch 108. This voltage appearsbetween the electrode 140 and the corresponding end of the pivot arm138. The resulting electrostatic force overcomes the spring force of thespring hinge 141 and causes the corresponding end to pivot via the pivothinge 141 about the rotation axis A_(R). The corresponding end is pulleddown toward the electrode 140 until the electrical contact 144 is liftedup from and no longer contacts the lower conductive strips 111. As aresult, the lower conductive strips 111 are no longer electricallyconnected.

The control circuit 103 of FIG. 1 is electrically connected to at leastone of the pivot blocks 142 and to both of the electrodes 139 and 140 ofeach see-saw switch 108. Thus, the application of the voltages foropening and closing each see-saw switch 108 is done under the control ofthe control circuit 103. In this way, the see-saw switch 108 providesthe switching function S of FIG. 3.

In an alternative configuration, other types of MEMS switches could beused instead o the MEMS see-saw switch 108. For example, a MEMS dockingswitch or a MEMS Derrick switch of the type described in copending PCTPatent Applications Ser. Nos. PCT/US00/16021 and PCT/US00/16023, havingrespective attorney docket nos. FP-68000/JAS/SMK and FP-68677/JAS/SMK,with rrespective titles MEMS TRANSMISSION AND CIRCUIT COMPONENTS andMEMS OPTICAL COMPONENTS, and filed on Jun. 9, 2000. These patentapplicatiions are incorporated by reference herein.

Referring back to FIGS. 1 and 2, each grid 101 is aligned in the beamcontroller 100 of FIG. 1 so that the E_(C)-plane and the H_(L)-plane ofeach unit cell 105 of the grid 101 are respectively perpendicular to theE_(b)-plane and the H_(b)-plane of the beam 104. As mentioned earlier,each unit cell 105 can be controllably reconfigured by the controlcircuit 103 of FIG. 1 to have a selected overall reactance that isprimarily inductive or primarily capacitive for producing acorresponding selected unit wide phase shift in the beam 104 in itsE_(b)-plane or its H_(b)-plane. This is done by selectively turning theswitch switching function S of FIG. 3 provided by the switch 108 of FIG.4 to be turned on or off and/or by selectively varying the inductivereactance L_(v) of FIG. 3 provided by the reconfigurable inductive strip106 of FIG. 4 and/or the capacitive reactance C, provided by thereconfigurable conductive strips 107 of FIG. 4. As a result, theelectric field E_(C) or the magnetic field H_(L) Of each unit cell 105can be correspondingly selected so as to cause the selected unit widephase shift in the E_(b)-plane or the H_(b)-plane.

As just described, the unit cells 105 in each grid 101 can be separatelycontrolled by the control circuit 103 in the manner just discussed toproduce a selected continuous phase shift for the grid 101. However,there may be phase coupling between adjacent unit cells 105 if theadjacent unit cells 105 are controlled differently to produce differentselected phase shifts. Thus, the unit cells 105 could be grouped inblocks as described later for the grids 154. Each block would beseparately controlled by the control circuit 103 with the unit cells 105in each block being jointly controlled in the same way to provide thesame overall reactance. This has the benefit of reducing phase couplingbetween adjacent unit cells 105, optimizing beam resolution, andsimplifying the control circuit 103 of FIG. 1.

As just mentioned, each unit cell 105 can be controllably reconfiguredby the control circuit 103 of FIG. 1 by appropriately controlling switch108 of FIG. 4 to turn on or off the switching function S of FIG. 3provided by the switch 108. However, as those skilled in the art willrecognize, if the switching function S is not desired, the switch 108could be removed from each unit cell 105. Also, the reconfigurableinductive strip 106 could be replaced by the fixed inductive strip 148of the unit cell 147 of FIG. 14 if a fixed inductive reactance L_(f) isdesired instead of the variable inductive reactance L_(v). Similarly,the reconfigurable capacitive strips 107 could be replaced by the fixedcapacitive strips 149 of the unit cell 147 of FIG. 14 if a fixedcapacitive reactance C_(f) is desired instead of the variable capacitivereactance C_(v).

Referring back to FIG. 4, as those skilled in the art will recognize,the unit cell 105 is not drawn to scale. This is done in order to betterillustrate the reconfigurability of the unit cell 105, namely the switch108 and the inductive and capacitive conductive strips 106 and 107. Morespecifically, the actuator assemblies 1 14 of the inductive andcapacitive conductive strips 106 and 107 would be much smaller and sowould the switch 108. Furthermore, preferably, the actuator assemblies114 of the inductive conductive strip 106 would in fact be located inthe lower conductive strips 134 of the capacitive conductive strips 107.This will make the actuator assemblies 114 invisible to the propagatingwaves of the beam 104 of FIG. 1.

Grids 146

Referring to FIG. 12, each of the grids 146 that could be used in thebeam controller 100 of FIG. 1 comprises reconfigurable unit cells 147.The unit cells 147 of each grid 146 are integrally formed together in aconfiguration to produce bean control in the E_(b)-plane of the beam 104of FIG. 1.

Referring to FIG. 13, the equivalent circuit for each unit cell 147 isthe same as that shown in FIG. 3 for each unit cell 105, except that theinductive and capacitive reactances L_(F) and C_(F) are fixed. Here, theoverall reactance of the unit cell 105 can be varied by simply turningthe switching function S on or off.

FIG. 14 shows one possible configuration for each unit cell 147 toprovide the equivalent circuit of FIG. 13. Each unit cell 147 isconfigured and operates similar to the unit cell 105 of FIG. 3 describedearlier. Thus, only the significant differences will be discussed next.

Each unit cell 147 comprises a fixed inductive strip 148 instead of thereconfigurable inductive strip 106 of the unit cell 105 of FIG. 4. Thefixed inductive strip 148 provides the fixed inductive reactance L_(f)in the equivalent circuit of FIG. 13 which produces the magnetic fieldH_(L) in the H_(L)-plane. Like the reconfigurable inductive strip 106,the fixed inductive strip 148 has a fixed length l_(f1) in the Xdirection. However, unlike the reconfigurable inductive strip 106, thefixed inductive strip 148 has a fixed width w_(f1) in the Y direction.The width w_(f1) is preferably about 2.3 mm for unit cell size of 20 mmper side to provide a binary unit wide phase shift of 22.5° at 5 GHz inthe beam 104 of FIG. 1 in the E_(b)-plane or the H_(b)-plane with phasechange and not amplitude change of the beam 104.

Each fixed fixed inductive strip 148 comprises two fixed conductivestrips 158 fixedly coupled to the dielectric layer 110. Similar to eachupper conductive strip 112 of each reconfigurable inductive strip 106 ofFIG. 5, each fixed conductive strip 158 comprises a semiconductor stripformed and a metal plating formed on the semiconductor strip. However,in this case the semiconductor strip is formed on the dielectric layer110. As with the reconfigurable inductive strip 106, the metal platingis used to reduce the resistivity of the fixed conductive strip 158caused by the semiconductor strip so as to avoid losses at millimeterand/or sub-millimeter wavelength frequencies of the beam 104 of FIG. 1.

Furthermore, each unit cell 147 comprises two parallel fixed capacitivestrips 149 instead of the reconfigurable conductive strips 107 of theunit cell 105 of FIG. 4. The fixed fixed capacitive strips 149 providethe fixed capacitive reactance C_(f) in the equivalent circuit of FIG.13. Here, the fixed capacitive reactance C_(f) is proportional to afixed gap g_(f)between the fixed capacitive strips 149 and produces themagnetic field H_(L) in the H_(L)-plane. Like each reconfigurablecapacitive strips 106, each fixed capacitive strip 149 has a fixedlength l_(f2) in the Y direction. However, unlike each reconfigurablecapacitive strips 106, each fixed capacitive strip 149 has a fixed widthw_(f1) in the X direction. The width w_(fl) is preferably about 2.3 mmto provide the binary phase shift in the beam 104 of FIG. 1 in theE_(b)-plane or the H_(b)-plane with phase change and not amplitudechange of the beam 104 for a unit cell size of 20 mm per side to providea binary unit wide phase shift of 22.5° at 5 GHz in the beam 104 of FIG.1 in the E_(b)-plane or the H_(b)-plane with phase change and notamplitude change of the beam 104.

Each fixed conductive strip 149 comprises two fixed conductive strips159 fixedly coupled to the dielectric layer 110. Similar to each upperconductive strip 112 of each reconfigurable inductive strip 106 of FIG.5, each fixed conductive strip 159 comprises a semiconductor strip and ametal plating formed on the semiconductor strip. However, in this casethe semiconductor strip is formed on the dielectric layer 110. As withthe reconfigurable inductive strip 106, the metal plating is used toreduce the resistivity of the fixed conductive strip 158 caused by thesemiconductor strip so as to avoid losses at millimeter and/orsub-millimeter wavelength frequencies of the beam 104 of FIG. 1.

Instead of the MEMS see-saw switch 108 of the unit cell 105 of FIG. 4,each unit cell 147 comprises PIN diode switch 150 that is electricallyconnected in series with the fixed conductive strips 158 of the fixedfixed inductive strip 148. This PIN diode switch 150 may be of the typedescribed in Stephan, K. et. al., “Quasi-optical Millimeter-Wave Hybridand Monolithic PIN Diode Switches”, IEEE Trans. Microwave Theory Tech.,pp. 1791 to 1798, October 1993. This article is incorporated byreference herein.

The PIN diode switch 150 provides the switching function S in theequivalent circuit of FIG. 13. Similar to the unit cell 105 of FIG. 4,the overall reactance of the unit cell 147 can be made primarilyinductive by causing the PIN diode switch 147 to electrically connectthe conductive strips 158 of the fixed fixed inductive strip 148 so asto close the switching function S. As a result, the inductive reactanceL_(f) of FIG. 13 provided by the fixed fixed inductive strip 148dominates the overall reactance of the unit cell 147. Conversely, theoverall reactance of the unit cell 148 can be made primarily capacitiveby causing the PIN diode switch 150 to electrically disconnect theconductive strips 158 so as to open the switching function S. As aresult, the capacitive reactance C_(f) of FIG. 13 provided by the fixedcapacitive strips 149 dominates the overall reactance of the unit cell147.

The anode and the cathode of the PIN diode switch 150 are fixedlycoupled and electrically connected to corresponding conductive strips158 of the fixed inductive strip 148. The anode of the PIN diode switch150 is electrically connected to the conductive strips 159 of acorresponding fixed capacitive strip 149 via the correspondingconductive strip 158 and a corresponding small interconnect 137.Similarly, the cathode of the PIN diode switch 150 is electricallyconnected to the conductive strips 159 of a corresponding fixedcapacitive strip 149 via the corresponding conductive strip 158 and acorresponding small interconnect 137.

The PIN diode switch 150 is closed and opened by respectively forwardand reverse biasing it. Specifically, to close the PIN diode switch 150,a forward bias DC voltage is applied across the conductive strips 159 ofthe corresponding fixed capacitive strip 149 electrically connected tothe anode and the conductive strips 159 of the corresponding fixedcapacitive strip 149 electrically connected to the cathode. This voltagethen appears across the anode and the cathode of the PIN diode switch150. Conversely, to closes the PIN diode switch 150, a reverse bias DCvoltage is applied across the conductive strips 159 electricallyconnected to the anode and the capacitive strips 159 electricallyconnected to the cathode. This voltage also appears across the anode andthe cathode of the PIN diode switch 150.

Each unit cell 147 can therefore be controllably reconfigured by thecontrol circuit 103 of FIG. 1 to have a selected overall reactance thatis primarily inductive or primarily capacitive for producing acorresponding binary unit wide phase shift in the beam 104 in itsE_(b)-plane or its H_(b)-plane. This is done by selectively turning theswitch switching function S of FIG. 13 provided by the PIN diode switch150 of FIG. 14 to be turned on or off. As a result, the electric fieldE_(C) or the magnetic field H_(L) of each unit cell 105 can becorrespondingly binarily changed so as to cause the binary unit widephase shift in the beam 104 of FIG. 1 in its E_(b)-plane or itsH_(b)-plane.

However, referring back to FIG. 12, the unit cells 147 are integrallyformed together in a configuration to produce beam control in theE_(b)-plane of the beam 104. This is done by grouping the unit cells 147in columns 151. Each column 151 is separately controlled by the controlcircuit 103 of FIG. 1 so that all of the unit cells 147 in the column151 will have the same overall reactance to provide a binary column widephase shift in the beam 104 in its E_(b)-plane.

Specifically, in each column 151, the fixed capacitive strips 149 thatare electrically connected to the anodes of the PIN diode switches 150of the unit cells 147 in the column 151 are fixedly coupled andelectrically connected together and, in fact, may be all integrallyformed together. Similarly, in each column 151, the fixed capacitivestrips 149 that are electrically connected to the cathodes of the PINdiode switches 150 of the unit cells 147 in the column are all fixedlycoupled and electrically connected together. They also may be allintegrally formed together. As a result, the PIN diode switches 150 ofthe unit cells 147 in each column 151 are electrically connected inparallel.

For each column 151, the control circuit 103 of FIG. 1 can thereforecause all of the PIN diode switches 150 of the unit cells 147 in thatcolumn 151 to be closed or opened. This is done by applying a forwardbias DC voltage or a reverse bias DC voltage across the two fixedcapacitive strips 149 of just one of these unit cells 147. As a result,this voltage appears across the anodes and cathodes of all of the PINdiode switches 150 of the unit cells 147. Since all of the PIN diodeswitches 150 will be closed or open in response, all of these unit cells147 will have the same overall reactance.

Referring back to FIGS. 1 and 12, each grid 146 is aligned in the beamcontroller 100 of FIG. 1 so that the E_(C)-plane of each unit cell 147of the grid 146 is perpendicular to the E_(b)-plane of the beam 104. Asmentioned earlier, the unit cells 147 in a column 151 will becontrollably reconfigured by the control circuit 103 of FIG. 1 in thesame way to have the same selected overall reactance for producing thesame corresponding binary unit wide phase shift in the beam 104 in itsE_(b)-plane. This is done by controlling the PIN diode switches 150 ofFIG. 14 of the unit cells 147 in the column 151 to turn on or off theircorresponding switching functions S of FIG. 13 so that the overallreactances of the unit cells 147 in the column 151 can all be madeprimarily inductive or primarily capacitive. The electric fields E_(C)of the unit cells 147 in the column 151 are therefore all binarilychanged in the same way to control the beam 104 in the same way in itsE_(b)-plane. This results in a corresponding binary column wide phaseshift in the E_(b)-plane.

By reconfiguring the unit cells 147 of columns 151 of a grid 146 in thisway, a corresponding discrete phase shift in the E_(b)-plane is achievedwith the grid 146. If multiple grids 146 are used in the beam controller100 of FIG. 1, the total phase shift in the E_(b)-plane that occursacross the grids 146 comprises progressive discrete phase shifts.

In an alternative configuration, a MEMS SiO₂ membrane switch could beused instead of the PIN diode switch 150. The configuration of each unitcell 147 and each grid 146 in this embodiment would be very similarsince such a membrane switch also requires forward and reverse bias DCvoltages for opening and closing it. This type of membrane switch isdisclosed in Chiao, J. C. et. al., “Microswitch Beam-Steering Grid”,IEEE Trans. Microwave Theory Tech., pp. 1791 to 1798, October 1993. Thisarticle is incorporated by reference herein.

As mentioned earlier, each unit cell 147 has the fixed inductive andcapacitive strips 148 and 149 of FIG. 14. However, as those skilled inthe art will recognize, each unit cell 147 could instead include thereconfigurable inductive and capacitive strips 106 and 107 of the unitcell 105 of FIG. 4. In this case, each unit cell 147 would becontrollably reconfigurable by the control circuit 103 of FIG. 1 to havea selected overall reactance for producing a corresponding selected unitwide phase shift in the beam 104 in the E_(b)-plane or H_(b)-plane. But,by reconfiguring the unit cells 147 of a column 151 to have the sameselected overall reactance, a corresponding selected column wide phaseshift in the E_(b)-plane can therefore be achieved with the column 151.Since this may be done with each column 151 of a grid 146, acorresponding discrete phase shift in the E_(b)-plane is achieved withthe grid 146. If multiple grids 146 are used in the beam controller 100of FIG. 1, the total phase shift in the E_(b)-plane that occurs acrossthe grids 146 comprises progressive continuous phase shifts.

Grids 152

Referring to FIG. 15, each of the grids 152 that could be used in thebeam controller 100 of FIG. 1 also comprises the reconfigurable unitcells 147. However, in contrast to each grid 146 of FIG. 10, the unitcells 147 are integrally formed together in a configuration on each grid152 to produce beam control in the H_(b)-plane of the beam 104 of FIG.1. Specifically, the unit cells are grouped in rows 153. Each row 153 isseparately controlled by the control circuit 103 of FIG. 1 so that allof the unit cells 147 in the row 153 will have the same overallreactance to provide a binary row wide phase shift in the beam 104 inits H_(b)-plane.

The fixed capacitive strips 149 and the small interconnects 137 ofadjacent unit cells 147 in each row 153 are fixedly coupled andelectrically connected. In fact, they may be integrally formed together.As a result, the PIN diode switches 150 of the unit cells 147 in eachrow 153 are electrically connected in series.

For each row 153, the control circuit 103 of FIG. 1 can therefore causeall of the PIN diode switches 150 of the unit cells 147 in that row 153to be closed or opened. This is done by applying a forward bias DCvoltage or a reverse bias DC voltage across the fixed capacitive strips149 of the last and first unit cells 147 of the row. As a result, aforward bias DC voltage or a reverse bias DC voltage appears across theanode and cathode of each PIN diode switch 150 of the unit cells of therow 153. Since all of these PIN diode switches 150 will be closed oropen in response, all of the unit cells 147 in the row 153 will have thesame reactance.

Referring back to FIGS. 1 and 13, each grid 152 is aligned in the beamcontroller 100 of FIG. 1 so that the H_(C)-plane of each unit cell 147of the grid 152 is perpendicular to the H_(b)-plane of the beam 104. Theunit cells 147 in each row 153 will be controllably reconfigured by thecontrol circuit 103 of FIG. 1 in the same way to have the same selectedoverall reactance for producing the same binary unit wide phase shift inthe beam 104 in the H_(b)-plane. This is done by controlling the PINdiode switches 150 of FIG. 14 of the unit cells 147 in the row 153 toturn on or off their corresponding switching functions S of FIG. 13 sothat the overall reactances of the unit cells 147 in the row 153 can allbe made primarily inductive or primarily capacitive. The magnetic fieldsH_(L) of the unit cells 147 in the row 153 are therefore all binarilychanged in the same way to control the beam 104 in the same way in itsH_(b)-plane. This results in a corresponding binary row wide phase shiftin the H_(b)-plane.

By reconfiguring the unit cells 147 of rows 153 of a grid 152 in thisway, a corresponding discrete phase shift in the H_(b)-plane is achievedwith the grid 152. If multiple grids 152 are used in the beam controller100 of FIG. 1, the total phase shift in the H_(b)-plane that occursacross the grids 152 comprises progressive discrete phase shifts.

In an alternative embodiment for each unit cell 147 in a grid 152, therecould be no physical coupling between the conductive strips 159 of eachfixed capacitive strip 149 and the corresponding conductive strip 158 ofthe fixed inductive strip 148. However, for millimeter andsub-millimeter wavelength frequencies of the beam 104 of FIG. 1, anelectrical connection still exists so that the equivalent circuit wouldstill be that shown in FIG. 13.

As mentioned for the grid 146 of FIG. 12, each unit cell 147 in eachgrid 152 could include the reconfigurable inductive and capacitivestrips 106 and 107 of the unit cell 105 of FIG. 4 instead of the fixedinductive and capacitive strips 148 and 149. Here, by reconfiguring theunit cells 147 of each row 153 to have the same selected overallreactance, a corresponding selected row wide phase shift in theH_(b)-plane can therefore be achieved with each grid 152. Since this maybe done with each row 153 of a grid 152, a corresponding discrete phaseshift in the H_(b)-plane is achieved with the grid 152. If multiplegrids 152 are used in the beam controller 100 of FIG. 1, the total phaseshift in the H_(b)-plane that occurs across the grids 152 comprisesprogressive continuous phase shifts.

Grids 154

Referring to FIG. 16, each of the grids 154 that could also be used inthe beam controller 100 of FIG. 1 comprises reconfigurable unit cells155. The unit cells are integrally formed together in a configuration oneach grid 152 to produce beam control in the E_(b)-plane and/or theH_(b)-plane of the beam 104 of FIG. 1. In contrast to the unit cells 105of the grid 101 of FIG. 2 and the unit cells 147 of the grid 146 of FIG.10, the unit cells 155 are grouped into blocks 156. Each block 156 isseparately controlled by the control circuit 103 of FIG. 1 so that allof the unit cells 155 in the block 155 will have the same overallreactance to provide a selected block wide phase shift in the beam 104in its E_(b)-plane or its H_(b)-plane.

Each unit cell 155 is configured and operates similar to the unit cell147 of FIG. 14 and implements the equivalent circuit of FIG. 13. Thus,only the significant differences will be discussed next.

Referring to FIG. 17, each unit cell 155 comprises a correspondingdielectric layer 110 on each of the opposite sides of the substrate 109.Like the unit cell 147 of FIG. 147 of FIG. 14, the unit cell 155 alsocomprises a corresponding fixed inductive strip 148 and a correspondingPIN diode switch 150 that are both formed on one dielectric layer 110.As with the unit cell 147, the fixed inductive strip 148 and acorresponding PIN diode switch 150 provide the fixed inductive reactanceL_(f) and the switching function S of the equivalent circuit of FIG. 13.However, in contrast to the unit cell 147, the unit cell 155 comprisescorresponding fixed capacitive strips 160 on the other dielectric layer110. The fixed capacitive strips 160 provide the fixed capacitivereactance C_(f) of the equivalent circuit of FIG. 13.

Similar to each upper conductive strip 112 of each reconfigurableinductive strip 106 of FIG. 5, each fixed conductive strip 160 comprisesa semiconductor strip and a metal plating formed on-the semiconductorstrip. However, in this case the semiconductor strip is formed on thedielectric layer 110. As with the reconfigurable inductive strip 106,the metal plating is used to reduce the resistivity of the fixedconductive strip 160 caused by the semiconductor strip so as to avoidlosses at millimeter and/or sub-millimeter wavelength frequencies of thebeam 104 of FIG. 1.

Furthermore, it is important to note here that there is no physicalcoupling between the fixed capacitive strips 160 and the fixed inductivestrip 148. However, for millimeter and sub-millimeter wavelengthfrequencies of the beam 104 of FIG. I, an electrical connection stillexists so that the equivalent circuit would still -be that shown in FIG.13. Therefore, the unit cell 155 would still provide a binary unit widephase shift in the beam 104 of FIG. 1 in its E_(b)-plane or itsH_(b)-plane. Since the fixed inductive and capacitive strips 148 and 160are on opposite sides of the unit cell 155, this binary unit wide phaseshift is optimized.

As mentioned earlier, the unit cells 155 are grouped in blocks 156. Eachblock 156 includes rows 161 and columns 162.

In each block 156, the conductive strips 158 of the fixed inductivestrips 148 of adjacent unit cells 155 in each row 161 are fixedlycoupled and electrically connected. In fact, they may be integrallyformed together. As a result, the PIN diode switches 150 of the unitcells 155 in each row 161 are electrically connected in series.

In addition, each block 156 comprises bias lines 163 formed on thedielectric layer 110 on which the fixed inductive strips 148 are formed.One bias line 163 fixedly couples and electrically connects together theconductive strips 158 of the fixed inductive strips 148 of unit cells155 in the first column 162 that are electrically connected to theanodes of the PIN diode switches 150 of these unit cells 155. This biasline 163 may be integrally formed together with these conductive strips158. The other bias line 163 fixedly couples and electrically connectstogether the conductive strips 158 of the fixed inductive strips 148 ofunit cells 155 in the last column 162 that are electrically connected tothe cathodes of the PIN diode switches 150 of these unit cells 155. Thisbias line 163 may be integrally formed together with these conductivestrips 158.

Furthermore, in each column 162 of each block 156, the fixed capacitivestrips 149 of the unit cells 155 in that column 162 that areelectrically connected to the anodes of the PIN diode switches 150 ofthese unit cells 155 are fixedly coupled and electrically connectedtogether and, in fact, may be all integrally formed together. Similarly,in each column 162 of each block 156, the fixed capacitive strips 149 ofthe unit cells 155 in that column 162 that are electrically connected tothe cathodes of the PIN diode switches 150 of these unit cells 155 arefixedly coupled and electrically connected together. They also may beall integrally formed together.

However, in an alternative configuration for each grid 154, the fixedcapacitive strips 149 of each unit cell 155 in each block 156 would notbe physically coupled to the fixed capacitive strips 149 of any otherunit cell 155 in the block 156. This is due to the fact that theequivalent circuit of FIG. 13 would still be the same for each unit cell155.

For each block 156, the control circuit 103 of FIG. 1 can thereforecause all of the PIN diode switches 150 of the unit cells 155 in thatblock 156 to be closed or opened. This is done by applying a forwardbias DC voltage or a reverse bias DC voltage across the bias lines 163of the block 156. As a result, this voltage appears across the anodesand cathodes of all of the PIN diode switches 150 of the unit cells 155.Since all of the PIN diode switches 150 will be closed or open inresponse, all of these unit cells 155 will have the same overallreactance.

Referring back to FIGS. 1 and 16, each grid 154 is aligned in the beamcontroller 101 of FIG. 1 so that the E_(C)-plane and the H_(L)-plane ofeach unit cell 155 of the grid 154 are respectively perpendicular to theE_(b)-plane and the H_(b)-plane of the beam 104. As mentioned earlier,the unit cells 155 in each block 156 will be controllably reconfiguredby the control circuit 103 of FIG. 1 in the same way to have the sameselected overall reactance for producing the same corresponding binaryunit wide phase shift in the beam 104 in its E_(b)-plane or itsH_(b)-plane. This is done by controlling the PIN diode switches 150 ofFIG. 14 of the unit cells 155 in the block 156 to turn on or off theircorresponding switching functions S of FIG. 13 so that the overallreactances of the unit cells 155 in the block 156 can all be madeprimarily inductive or primarily capacitive. The electric fields E_(C)or the magnetic fields H_(L) of the unit cells 147 in the column 151 aretherefore all binarily changed in the same way to control the beam 104in the same way in its E_(b)-plane or its H_(b)-plane. This results in acorresponding binary block wide phase shift in the E_(b)-plane or theH_(b)-plane.

By reconfiguring the unit cells 155 of blocks 156 of a grid 154 in thisway, a corresponding discrete phase shift in the E_(b)-plane is achievedwith the grid 154. If multiple grids 154 are used in the beam controller100 of FIG. 1, the total phase shift in the E_(b)-plane or H_(b)-planethat occurs across the grids 154 comprises progressive discrete phaseshifts.

As was discussed earlier for the grids 101 of FIG. 2, grouping the unitcells 155 of each grid 154 in blocks 156 has several advantages. Itreduces phase coupling between adjacent unit cells 155, optimizes beamresolution, and simplifies the control circuit 103 of FIG. 1.

As with the unit cells 147 of the grids 146 and 152 of FIGS. 12 and 15,each unit cell 155 in each grid 152 could include the reconfigurableinductive and capacitive strips 106 and 107 of the unit cell 105 of FIG.4 instead of the fixed inductive and capacitive strips 148 and 160.Similar to each unit cell 147 in this case, each unit cell 155 would becontrollably reconfigurable by the control circuit 103 of FIG. 1 to havea selected overall reactance for producing a corresponding selected unitwide phase shift in the beam 104 in the E_(b)-plane or H_(b)-plane. But,by reconfiguring the unit cells 155 of each block 156 to have the sameselected overall reactance, a corresponding selected block wide phaseshift in the E_(b)-plane or the H_(b)-plane can therefore be achievedwith each grid 154. Since this may be done with each block 156 of a grid154, a corresponding selected continuous phase shift in the E_(b)-planeor the H_(b)-plane is achieved with the grid 154. If multiple grids 154are used in the beam controller 100 of FIG. 1, the total phase shift inthe E_(b)-plane or the H_(b)-plane that occurs across the grids 154comprises progressive continuous phase shifts.

Fabrication Process

The grids 101, 146, and 154 may be fabricated using a three polysiliconlayer process. This of course also means that the unit cells 105, 147,and 155 may each be formed with this same three polysilicon layerprocess. The composition of the various elements of these unit cells105, 147, and 155 are identified in FIGS. 1 to 17 and therefore will notbe specifically identified here.

In this process, a dielectric layer identified as dielectric layer 1 10in FIGS. 1 to 17 is first deposited on a semiconductor substrateidentified as substrate 109 in FIGS. 1 to 17. The substrate may comprisesilicon and the insulating layer may comprise silicon nitride.

Then, a first polysilicon layer (poly 0) is deposited on the dieletriclayer. This polysilicon layer is selectively patterned on the dielectriclayer to form the elements identified in the FIGS. 1 to 17 as being poly0.

A first sacrificial layer, such as a PSG (phosphorous silicate glass)like silicon dioxide, is then deposited on the dielectric layer and thepatterned first polysilicon layer. This sacrificial layer is thenselectively etched down to form openings for the formation of theelements identified as anchor 1 and 2. This sacrificial layer is alsoselectively etched to form dimples in it for the formation of contactrails.

A second polysilicon layer (poly 1) is then deposited on the firstsacrificial layer and in the openings and dimples just mentioned. Thispolysilicon layer is then selectively patterned to form the elementsidentified as poly 1 and anchor 1 and the lower portions of the elementsidentified as anchor 2.

A first insulating layer (insulating 1) is then deposited on the firstsacrificial layer and the patterned second polysilicon layer. Like thedielectric layer, this insulating layer may comprise silicon nitride.The first insulating layer is then selectively patterned to form theelements identified as insulating 1.

A second sacrificial layer that is of the same material as the firstsacrificial layer is then deposited on the first sacrificial layer, thepatterned second polysilicon layer, and the patterned first insulatinglayer. The second sacrificial layer is selectively etched down to thelower portions of the elements identified as anchor 2 for the formationof the upper portion of these elements. The second sacrificial layer isalso selectively etched to provide openings for the formation of theelements identified as via. The second sacrificial layer is furtherselectively etched to form dimples in the second sacrificial layer forthe formation of bushings of SDAs.

A third polysilicon layer (poly 2) is then deposited on the secondsacrificial layer and in the openings and dimples just mentioned. Thispolysilicon layer is then selectively patterned to form the upperportions of the elements identified as anchor 2 and the elementsidentified as poly 2.

A third sacrificial layer is then deposited on the second sacrificiallayer and the patterned third polysilicon layer. This third sacrificiallayer is of the same material as the first and second sacrificiallayers. This sacrificial layer is then selectively etched down to formopenings for metal evaporation deposition of a metal layer, such asgold, on any of the elements identified as being poly 2 for which thisis desired. Then, this metal layer is deposited.

Then, the first, second, and third sacrificial layers may be selectivelyetched to expose any elements identified as poly 0, poly 1, poly 2 formetal electroplating deposition of a metal layer, such as gold, on anyof these elements for which it is desired and for those of the elementsthat are identified as electroplating. This is done by placing theentire grid 101, 146, or 154 or unit cell 105, 147, or 155 in a solutioncontaining the metal and then applying an appropriate voltage to theexposed element.

Finally, the first, second, and third sacrificial layers are entirelyremoved. This frees all of the moving elements for movement in themanner described earlier.

Conclusion

As those skilled in the art will recognize the unit cells 105, 147, and155, the grids 101, 146, and 154, and their various other embodimentsdescribed herein can be used in other quasi-optical systems. Forexample, they can be used in quasi-optical nonisotropitc filters,nonlinear surfaces, polarization rotators, impedance tuners, phaseshifters, amplitude modulators, power splitters, front-end switchingarrays, power linearizers, limiters, phase-locked loops, active feedbackloops, etc.

Furthermore, while the present invention has been described withreference to a few specific embodiments, the description is illustrativeof the invention and is not to be construed as limiting the invention.Various modifications may occur to those skilled in the art withoutdeparting from the true spirit and scope of the invention as defined bythe appended claims.

What is claimed is:
 1. A quasi-optical unit cell for use in aquasi-optical grid to control an incident beam to the quasi-opticalgrid, the unit cell comprising: an inductive conductive strip configuredto provide an inductive reactance; and capacitive conductive strips toprovide a capacitive reactance; wherein at least one of the inductivestrip and the capacitive strips are controllably reconfigurable toprovide the unit cell with a variable overall reactance for producing avariable phase shift in the incident beam.
 2. A quasi-optical grid foruse in a quasi-optical system to control an incident beam to thequasi-optical system, the quasi-optical grid comprising quasi-opticalunit cells, each of the quasi-optical unit cells comprising: aninductive conductive strip configured to provide an inductive reactance;and capacitive conductive strips to provide a capacitive reactance;wherein at least one of the inductive strip and the capacitive stripsare controllably reconfigurable to provide the unit cell with a variableoverall reactance for producing a variable phase shift in the incidentbeam.
 3. A quasi-optical system for control an incident beam to thequasi-optical system, the quasi-optical system comprising: quasi-opticalgrids, each of the quasi-optical grids comprising quasi-optical unitcells, each quasi-optical unit cell comprising an inductive conductivestrip configured to provide an inductive reactance and capacitiveconductive strips to provide a capacitive reactance; and a controlcircuit configured to controllably reconfigure at least one of theinductive strip and the capacitive strips to provide the unit cell witha variable overall reactance for producing a variable phase shift in theincident beam.
 4. A quasi-optical unit cell for use in a quasi-opticalgrid to control an incident beam to the quasi-optical grid, the unitcell comprising: an inductive conductive strip configured to provide aninductive reactance; capacitive conductive strips configured to providea capacitive reactance; a switch configured to provide a switchingfunction; wherein: the unit cell has an overall reactance in which theinductive reactance and the switching function are in series with eachother and in parallel with the capacitive reactance, the overallreactance being primarily inductive or primarily capacitive when theswitch is controlled so that the switching function is on or off; andthe inductive and capacitive strips are configured so that the overallreactance causes a phase shift in but not an amplitude distortion in theincident beam.
 5. A quasi-optical grid for use in a quasi-optical systemto control an incident beam to the quasi-optical system, thequasi-optical grid comprising quasi-optical unit cells, each of thequasi-optical unit cells comprising: an inductive conductive stripconfigured to provide an inductive reactance; capacitive conductivestrips configured to provide a capacitive reactance; a switch configuredto provide a switching function; wherein: the unit cell has an overallreactance in which the inductive reactance and the switching functionare in series with each other and in parallel with the capacitivereactance, the overall reactance being primarily inductive or primarilycapacitive when the switch is controlled so that the switching functionis on or off; and the inductive and capacitive strips are configured sothat the overall reactance causes a phase shift in but not an amplitudedistortion in the incident beam.
 6. A quasi-optical system for controlan incident beam to the quasi-optical system, the quasi-optical systemcomprising: quasi-optical grids, each of the quasi-optical gridscomprising quasi-optical unit cells, each quasi-optical unit cellcomprising an inductive conductive strip configured to provide aninductive reactance, capacitive conductive strips to provide acapacitive reactance, and a switch configured to provide a switchingfunction, the unit cell having an overall reactance in which theinductive reactance and the switching function are in series with eachother and in parallel with the capacitive reactance, the inductive andcapacitive strips are configured so that the overall reactance causes aphase shift in but not an amplitude distortion in the incident beam; anda control circuit configured to control the switch to turn the switchingfunction on or off to cause the overall reactance to be primarilyinductive or primarily capacitive.
 7. A quasi-optical unit cell for usein a quasi-optical grid to control an incident beam to the quasi-opticalgrid, the unit cell comprising: a substrate having opposite first andsecond sides; a first dielectric layer on the first side of thesubstrate; a second dielectric layer on the second side of thesubstrate; an inductive conductive strip on the first dielectric layerthat is configured to provide an inductive reactance; capacitiveconductive strips on the second dielectric layer configured to provide acapacitive reactance; a switch on the first dielectric layer that isconfigured to provide a switching function; wherein the unit cell has anoverall reactance in which the inductive reactance and the switchingfunction are in series with each other and in parallel with thecapacitive reactance, the overall reactance being primarily inductive orprimarily capacitive when the switch is controlled so that the switchingfunction is on or off.
 8. A quasi-optical grid for use in aquasi-optical system to control an incident beam to the quasi-opticalsystem, the quasi-optical grid comprising quasi-optical unit cells, eachof the quasi-optical unit cells comprising: a substrate having oppositefirst and second sides; a first dielectric layer on the first side ofthe substrate; a second dielectric layer on the second side of thesubstrate; an inductive conductive strip on the first dielectric layerthat is configured to provide an inductive reactance; capacitiveconductive strips on the second dielectric layer configured to provide acapacitive reactance; a switch on the first dielectric layer that isconfigured to provide a switching function; wherein the unit cell has anoverall reactance in which the inductive reactance and the switchingfunction are in series with each other and in parallel with thecapacitive reactance, the overall reactance being primarily inductive orprimarily capacitive when the switch is controlled so that the switchingfunction is on or off, respectively.
 9. A quasi-optical system forcontrol an incident beam to the quasi-optical system, the quasi-opticalsystem comprising: quasi-optical grids, each of the quasi-optical gridscomprising quasi-optical unit cells, each quasi-optical unit cellcomprising: a substrate having opposite first and second sides; a firstdielectric layer on the first side of the substrate; a second dielectriclayer on the second side of the substrate; an inductive conductive stripon the first dielectric layer that is configured to provide an inductivereactance; capacitive conductive strips on the second dielectric layerconfigured to provide a capacitive reactance; a switch on the firstdielectric layer that is configured to provide a switching function;wherein the unit cell has an overall reactance in which the inductivereactance and the switching function are in series with each other andin parallel with the capacitive reactance; and a control circuitconfigured to control the switch to turn the switching function on oroff to cause the overall reactance to be primarily inductive orprimarily capacitive.